The present invention is concerned with digital data recording and playback apparatus which includes an optical recording and playback device, and which is capable of recording and retrieving digital data representing digital or analog signals onto and from an optical storage card at high speeds.
The apparatus of the invention finds utility in the system described in co-pending application Ser. No. 619,098 filed Nov. 28, 1990, and assigned to the present assignee. The apparatus of the invention is of the same general type as the optical recording and playback apparatus described in co-pending application Ser. No. 845,331 filed Feb. 10, 1992, likewise assigned to the present assignee.
Co-pending application Ser. No. 619,098 discloses a digital broadcast system for the transmission of production quality stereo audio program material, video program material and other data. The system of application Ser. No. 619,098 comprises a number of transceiver units, each capable of operating in each of several modes, that is, in a recording, transmitting, receiving and playback mode. In the transmitting mode, one of the transceiver units in the system is capable of transmitting video or stereo audio data in digital form, either in real time or at high speeds, to other transceiver units over a selected common channel, such as fiber optic, cellular UHF, microwave, or satellite. In the receiving mode, the transceiver unit is capable of receiving data from other units of the system in digital form, and of converting the received data back to its original analog form.
The data storage card which is used in conjunction with the optical recording and playback head of co-pending application Ser. No. 845,331, and in conjunction with the apparatus of the present invention, is an optically encoded data storage card which may be of a size, for example, of a usual credit card. Both sides of the card may be utilized, and the card may have the capability of storing approximately one-half gigabyte of digital data on each side, this being the equivalent of approximately one double-sided record album per side, without compression of data.
Unlike the usual prior art video or compact disk, the optical storage card used in the system to be described does not spin. The elimination of the prior art mechanical compact disk drive, and other requirements, in the system of the invention results in significant accelerated write and access speeds and cost reduction.
The optical recording and playback head of co-pending application Ser. No. 845,331 includes a multiplicity of miniature lasers arranged in rows and columns. The lasers are directed to the data storage card. In the write or record mode, data is stored on the card by the lasers. In the read or playback mode, the data previously stored on the card is retrieved by the use of lasers and photo diodes. The apparatus of the present invention, as will be described, also includes a recording and playback laser head comprising a multiplicity of lasers, and photo diodes similar in some respects to the head described in co-pending application Ser. No. 845,331. However, in the apparatus of the present invention, the data storage card itself is moved in the X- and Y-directions for scanning purposes, whereas in the apparatus of co-pending application Ser. No. 845,331 the laser beams are scanned over the data storage card while the card is held in a stationary position.
The digital data optical recording and playback apparatus of the invention, in the specific embodiment to be described, comprises an optical head consisting of a flat two-dimensional array of laser diodes and photo diodes. The data storage card on which digital data is to be recorded is positioned below the laser and photo diode array, and a mechanism is provided to move the card in both the X- and Y-directions to position the array of lasers and photo diodes over any one particular location (out of 1,000.times.1,000=1,000,000) on the card.
The laser and photo diode array may consist, for example, of 4,000 elements arranged in a two-dimensional manner, with each element consisting of one laser diode and one photo diode.
An electronic section is also provided in the apparatus for multiplexing signals applied to and derived from the laser diode and photo diode array, and also to interface the optical head of the apparatus with a central processing unit (CPU).